Tap the blue circles to see an explanation.
| $$ \begin{aligned}(x+4)(x-15)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x^2-15x+4x-60 \xlongequal{ } \\[1 em] & \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle2}{\textcircled {2}} } }}}x^2-11x-60\end{aligned} $$ | |
| ① | Multiply each term of $ \left( \color{blue}{x+4}\right) $ by each term in $ \left( x-15\right) $. $$ \left( \color{blue}{x+4}\right) \cdot \left( x-15\right) = x^2-15x+4x-60 $$ |
| ② | Combine like terms: $$ x^2 \color{blue}{-15x} + \color{blue}{4x} -60 = x^2 \color{blue}{-11x} -60 $$ |